WASHINGTON — Two psychiatric patients at a veterans facility in Brockton received no regular evaluations of their condition for years, part of a “troubling pattern of deficient patient care” that federal investigators say they have confirmed at veterans health care facilities nationwide.

One of the neglected patients at the Brockton Community Living Center who had been admitted for “significant and chronic mental health issues” was living in the 106-bed facility for eight years before he received his first psychiatric evaluation, investigators reported.

The other unidentified patient, although he was classified as 100 percent mentally disabled due to his military service, had only a single “psychiatric note” placed in his medical file between 2005 and 2013.

The findings by the federal Office of Special Counsel, an independent agency that investigates and prosecutes wrongdoing in the civil service, were contained in a nationwide review of 10 cases in which Department of Veterans Affairs employees came forward as whistle-blowers with complaints about substandard care and practices.

The new findings indicate that sizable numbers of patients may be receiving substandard medical care and that the VA has failed to correct problems despite being made aware of them. The latest revelations go beyond the recent reports of problems in the VA health care system, which have largely centered on long delays for veterans seeking appointments for outpatient specialty care, particularly at a Phoenix, Ariz., veterans hospital.

The Office of Special Counsel says it is investigating more than 50 whistle-blower disclosures at the VA nationwide. It is reviewing even more cases — approximately 60 — of allegations that those who came forward with concerns about scheduling, understaffing, and patient care faced retaliation by their superiors.

In Brockton and other cases, the agency found that the VA, after conducting its own investigations that corroborated the allegations, nevertheless insisted there was no impact on patient well-being.

“Such statements are a serious disservice to the veterans who receive inadequate care for years after being admitted to VA facilities,” Carolyn N. Lerner, the top official of Office of Special Counsel, wrote in a letter to President Obama outlining her findings on Monday.

Vincent Ng, medical director of the Boston VA Health Care System — which includes facilities in Brockton, Jamaica Plain, and West Roxbury — declined to address the specific allegations. But he said in a statement that he encourages whistle-blowers to come forward.

“When staff, patients, and the public identify and voice areas of concern in veteran care, we can work together to find solutions and through regular mental health consultations continue to give our veterans the care they earned and deserve,” Ng said.

Acting Secretary of Veterans Affairs Sloan Gibson said in a statement that he is “deeply disappointed not only in the substantiation of allegations raised by whistle-blowers but also in the failures within VA to take whistle-blower complaints seriously.”

Gibson, who took the reins of the embattled agency last month after the resignation of VA Secretary Eric Shinseki, said he had ordered a two-week review of the VA’s Office of the Medical Inspector, which reviewed many of the initial claims of the whistle-blowers.

“This will include a review of process, structure, resourcing, and how recommendations are tracked and reviewed,” Gibson said. “Additionally, this review will include consideration of personnel actions and will designate an official to assess the conclusions and the proposed corrective actions.”

The government-run VA health care system is the largest integrated health care system in the country, treating more than six million patients each year.

The Office of Special Counsel found numerous cases across the country that suggest serious medical malpractice is not unusual.

For example, the agency corroborated a case in Alabama that found old notes were copied and classified as “current readings” in the files of more than 1,200 patients, “likely resulting in inaccurate patient health information being recorded.”

In Buffalo, medical staff incorrectly labeled sterile surgical instruments; in San Juan, investigators found that “nursing staff neglected elderly residents by failing to assist with essential daily activities, such as bathing, eating, and drinking.”

In Brockton, investigators focused on two patients in the Center for Community Living, which officials described as providing both short- and long-term care for a mix of patients, including those suffering from dementia, those in need of hospice care, and others undergoing rehabilitation after surgery.

The first patient arrived at the facility in 2003 “with significant and chronic mental health issues,” according to Lerner’s letter to Obama. “Yet, his first comprehensive psychiatric evaluation did not occur until 2011, more than eight years after he was admitted, when he was assessed by the whistle-blower. No medication assessments or modifications occurred until the 2011 consultation.”

The other patient, described as “a veteran with a 100 percent service-connected psychiatric condition,” was a resident of the facility from 2005 to 2013.

“In that time, he had only one psychiatric note written is his medical chart, in 2012, when he was first examined by the whistle-blower, more than seven years after he was admitted,” the agency found.

The response from the Boston VA indicates patients also may have been overmedicated. A spokeswoman said that officials have already taken steps to address the specific allegations about the Brockton facility, including instituting “regular psychiatric consultation services, staff education for all team members, use of alternatives to potent psychiatric medications whenever possible, and regular medication reviews.”

The Brockton whistle-blower, a staff psychiatrist, was not identified in the report. Contacted by the Globe, he declined to comment, citing ongoing litigation related to his case, including his allegation that he was retaliated against by his superiors.

In the Brockton cases as well as others across the country, investigators found it commonplace for the VA to corroborate allegations by whistle-blowers but then dismiss any possibility that patients suffered.

“This approach has prevented the VA from acknowledging the severity of systemic problems and from taking the necessary steps to provide quality care to veterans,’’ Lerner told Obama. “As a result, veterans’ health and safety has been unnecessarily put at risk.”